CN107370533B - Method, device and system for carrying out analog CSI feedback - Google Patents

Abstract

The invention provides a method for carrying out analog CSI feedback in user equipment, wherein the method comprises the following steps: a, obtaining an analog CSI matrix corresponding to user equipment, wherein the analog CSI matrix meets the following conditions: x XH ═ D; wherein X represents an analog CSI matrix, H represents a conjugate transpose of the matrix, and D represents a diagonal matrix; and b, acquiring main element information corresponding to the analog CSI matrix according to preset index information, and sending the main element information to a base station. According to the scheme of the invention, the feedback overhead can be greatly reduced, the CSI feedback quality is higher, and the reliable CSI recovery can be realized on the base station side.

Description

Method, device and system for carrying out analog CSI feedback

Technical Field

The present invention relates to the field of communications technologies, and in particular, to a method, an apparatus, and a system for simulating CSI feedback in a communication system.

Background

In the prior art, a base station can directly obtain CSI (Channel State Information) fed back by User Equipment (UE), and in an actual system (e.g., LTE/LTE-a), the currently adopted CSI feedback scheme is codebook-based limited feedback, which is a digital solution. However, for 4G systems, 5G systems and more advanced communication systems that may appear in the future, the above-described digitized solutions have the following problems:

1) for large antenna arrays (e.g., 64, 128, etc. port count), design complexity becomes higher;

2) the larger the codebook size is, the higher the complexity of determining the optimal codeword at the UE side becomes;

3) the effectiveness of the structured codebook depends on the characteristics of the Channel, such as Channel correlation, and therefore CSI feedback using an equivalent Channel based on a beamformed CSI-RS (Channel state Information Reference Signal), such as defined in R13 of LTE, may not be applicable;

4) the above solution based on the performance of the current codebook has SNR dependency, i.e. when the SNR increases, there is a false floor;

5) the accuracy of the above solution is poor because the uplink feedback channel resources are limited and the coding and decoding efficiency is not satisfactory.

In response to the above problems, the concept of Analog Feedback (Analog Feedback) is currently proposed, which allows the UE to report only unquantized and uncoded versions of the downlink channel information. However, no specific implementation of analog CSI feedback has been provided in the prior art.

Disclosure of Invention

The invention aims to provide a method, a device and a system for simulating CSI feedback in a communication system.

According to an aspect of the present invention, there is provided a method for analog CSI feedback in a user equipment, wherein the method comprises:

a, obtaining an analog CSI matrix corresponding to user equipment, wherein the analog CSI matrix meets the following conditions:

X X^H＝D

wherein X represents an analog CSI matrix, H represents a conjugate transpose of the matrix, and D represents a diagonal matrix;

and b, acquiring main element information corresponding to the analog CSI matrix according to preset index information, and sending the main element information to a base station.

According to another aspect of the present invention, there is also provided a method in a base station for obtaining an analog CSI matrix corresponding to a user equipment, wherein the method includes:

a, receiving main element information corresponding to an analog CSI matrix from user equipment;

b, obtaining the analog CSI matrix according to preset index information and the main element information;

wherein the analog CSI matrix satisfies the following conditions:

X X^H＝D

where X represents the analog CSI matrix, H represents the conjugate transpose of the matrix, and D represents the diagonal matrix.

According to another aspect of the present invention, there is also provided a first apparatus for analog CSI feedback in a user equipment, wherein the first apparatus includes:

a first obtaining device, configured to obtain an analog CSI matrix corresponding to a user equipment, where the analog CSI matrix satisfies the following condition:

X X^H＝D

wherein X represents an analog CSI matrix, H represents a conjugate transpose of the matrix, and D represents a diagonal matrix;

and the first sending device is used for obtaining the main element information corresponding to the analog CSI matrix according to the preset index information and sending the main element information to the base station.

According to another aspect of the present invention, there is also provided a second apparatus in a base station for obtaining an analog CSI matrix corresponding to a user equipment, wherein the second apparatus includes:

first receiving means for receiving principal element information corresponding to the analog CSI matrix from the user equipment;

second obtaining means for obtaining the analog CSI matrix according to the main element information and predetermined index information;

wherein the analog CSI matrix satisfies the following conditions:

X X^H＝D

where X represents the analog CSI matrix, H represents the conjugate transpose of the matrix, and D represents the diagonal matrix.

According to another aspect of the present invention, there is also provided a system for analog CSI feedback, where the system includes a base station and a user equipment, the user equipment includes the first apparatus of the present invention, and the base station includes the second apparatus of the present invention.

According to another aspect of the present invention, there is also provided a method for analog CSI feedback in a user equipment, wherein the method comprises:

x, decomposing a channel covariance matrix to obtain a main basis vector of a subspace of channel statistics, and determining a first analog matrix corresponding to the user equipment according to the main basis vector;

y, estimating a linear combination matrix corresponding to the first analog matrix according to a downlink reference signal from a base station;

and z, sending the first simulation matrix to a base station in a long period mode, and sending the associated feedback information corresponding to the linear combination matrix to the base station in a short period mode.

According to another aspect of the present invention, there is also provided a method in a base station for obtaining CSI feedback information corresponding to a user equipment, wherein the method comprises:

receiving a first analog matrix sent to the base station by user equipment in a long period mode and associated feedback information corresponding to a linear combination matrix sent to the base station in a short period mode;

and obtaining CSI feedback information corresponding to the user equipment according to the first simulation matrix and the associated feedback information.

According to another aspect of the present invention, there is also provided a third apparatus for analog CSI feedback in a user equipment, wherein the third apparatus includes:

third obtaining means for obtaining a master basis vector of a subspace of channel statistics by decomposing a channel covariance matrix, and determining a first analog matrix corresponding to the user equipment according to the master basis vector;

estimating means for estimating a linear combination matrix corresponding to the first analog matrix according to a downlink reference signal from a base station;

and the second sending device is used for sending the first analog matrix to a base station in a long period mode and sending the associated feedback information corresponding to the linear combination matrix to the base station in a short period mode.

According to another aspect of the present invention, there is also provided a fourth apparatus in a base station for obtaining CSI feedback information corresponding to a user equipment, wherein the fourth apparatus includes:

a second receiving device, configured to receive a first analog matrix sent by a user equipment to the base station in a long-period mode, and associated feedback information corresponding to a linear combination matrix sent to the base station in a short-period mode;

and a fourth obtaining device, configured to obtain CSI feedback information corresponding to the ue according to the first analog matrix and the associated feedback information.

According to another aspect of the present invention, there is also provided a system for analog CSI feedback, where the system includes a base station and a user equipment, the user equipment includes the third apparatus of the present invention, and the base station includes the fourth apparatus of the present invention.

Compared with the prior art, the invention has the following advantages: by sending the main element information corresponding to the analog CSI matrix to the base station, the feedback overhead can be reduced to a great extent, and better CSI recovery quality can be realized at the base station due to the fact that the power is concentrated on the main element information; in addition, the feedback process is divided into two stages, the main element information corresponding to the first simulation matrix is sent in a long period mode, and the main element information corresponding to the second simulation matrix is sent in a short period mode, so that the feedback overhead can be further reduced; in addition, since the analog CSI matrix satisfies X X^HThe condition of D can be directly used for further precoding and beamforming, thus simplifying the implementation at the base station.

Drawings

Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments made with reference to the following drawings:

fig. 1 is a flow chart illustrating a method for analog CSI feedback according to an embodiment of the present invention;

fig. 2 is a schematic flow chart of a method for analog CSI feedback according to another embodiment of the present invention;

fig. 3 is a schematic structural diagram of a system for analog CSI feedback according to an embodiment of the present invention;

fig. 4 is a schematic structural diagram of a system for analog CSI feedback according to an embodiment of the present invention;

fig. 5 is a schematic diagram of an exemplary analog CSI matrix of the present invention.

The same or similar reference numbers in the drawings identify the same or similar elements.

Detailed Description

While the exemplary embodiments are susceptible to various modifications and alternative forms, certain embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that there is no intention to limit example embodiments to the specific forms disclosed, but on the contrary, example embodiments are to cover all modifications, equivalents, and alternatives falling within the scope of the claims. Like reference numerals refer to like elements throughout the description of the various figures.

Before discussing exemplary embodiments in more detail, it should be noted that some exemplary embodiments are described as processes or methods depicted as flowcharts. Although a flowchart may describe the operations as a sequential process, many of the operations can be performed in parallel, concurrently, or simultaneously. In addition, the order of the operations may be re-arranged. The process may be terminated when its operations are completed, but may have additional steps not included in the figure. The processes may correspond to methods, functions, procedures, subroutines, and the like.

The term "wireless device" or "device" as used herein may be considered synonymous with and sometimes hereinafter referred to as: a client, user equipment, mobile station, mobile user, mobile terminal, subscriber, user, remote station, access terminal, receiver, mobile unit, etc., and may describe a remote user of wireless resources in a wireless communication network.

Similarly, the term "base station" as used herein may be considered synonymous with, and sometimes referred to hereinafter as: a node B, an evolved node B, an eNodeB, a Base Transceiver Station (BTS), an RNC, etc., and may describe a transceiver that communicates with and provides radio resources to a mobile in a wireless communication network that may span multiple technology generations. The base stations discussed herein may have all of the functionality associated with conventional well-known base stations, except for the ability to implement the methods discussed herein.

The methods discussed below, some of which are illustrated by flow diagrams, may be implemented by hardware, software, firmware, middleware, microcode, hardware description languages, or any combination thereof. When implemented in software, firmware, middleware or microcode, the program code or code segments to perform the necessary tasks may be stored in a machine or computer readable medium such as a storage medium. The processor(s) may perform the necessary tasks.

Specific structural and functional details disclosed herein are merely representative and are provided for purposes of describing example embodiments of the present invention. The present invention may, however, be embodied in many alternate forms and should not be construed as limited to only the embodiments set forth herein.

It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element may be termed a second element, and, similarly, a second element may be termed a first element, without departing from the scope of example embodiments. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

It will be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being "directly connected" or "directly coupled" to another element, there are no intervening elements present. Other words used to describe the relationship between elements (e.g., "between" versus "directly between", "adjacent" versus "directly adjacent to", etc.) should be interpreted in a similar manner.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used herein, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

It should also be noted that, in some alternative implementations, the functions/acts noted may occur out of the order noted in the figures. For example, two figures shown in succession may, in fact, be executed substantially concurrently, or the figures may sometimes be executed in the reverse order, depending upon the functionality/acts involved.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which example embodiments belong. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

Portions of the exemplary embodiments and corresponding detailed description are presented in terms of software, or algorithms and symbolic representations of operations on data bits within a computer memory. These descriptions and representations are the ones by which those of ordinary skill in the art effectively convey the substance of their work to others of ordinary skill in the art. An algorithm, as the term is used here, and as it is used generally, is conceived to be a self-consistent sequence of steps leading to a desired result. The steps are those requiring physical manipulations of physical quantities. Usually, though not necessarily, these quantities take the form of optical, electrical, or magnetic signals capable of being stored, transferred, combined, compared, and otherwise manipulated. It has proven convenient at times, principally for reasons of common usage, to refer to these signals as bits, values, elements, symbols, characters, terms, numbers, or the like.

In the following description, the illustrative embodiments will be described with reference to acts and symbolic representations of operations (e.g., in the form of flowcharts) that can be implemented as program modules or functional processes including routines, programs, objects, components, data structures, etc., that perform particular tasks or implement particular abstract data types and that can be implemented using existing hardware at existing network elements. Such existing hardware may include one or more Central Processing Units (CPUs), Digital Signal Processors (DSPs), application specific integrated circuits, Field Programmable Gate Arrays (FPGAs) computers, and the like.

It should be recognized that all of these and similar terms are to be associated with the appropriate physical quantities and are merely convenient labels applied to these quantities. Unless specifically stated otherwise, or as is apparent from the discussion, terms such as "processing," "computing," "determining," or "displaying" or the like, refer to the action and processes of a computer system, or similar electronic computing device, that manipulates and transforms data represented as physical, electronic quantities within the computer system's registers and memories into other data similarly represented as physical quantities within the computer system memories or registers or other such information storage, transmission or display devices.

It should also be noted that the software implemented aspects of the exemplary embodiments are typically encoded on some form of program storage medium or implemented over some type of transmission medium. The program storage medium may be a magnetic (e.g., floppy disk or hard drive) or optical (e.g., compact disk read only memory or "CD ROM") storage medium, and may be a read only or random access storage medium. Similarly, the transmission medium may be twisted wire pairs, coaxial cable, optical fiber, or some other suitable transmission medium known to the art. The exemplary embodiments are not limited by these aspects of any given implementation.

The processor and memory may operate together to perform device functions. For example, the memory may store code segments relating to the functionality of the device. The code segments may in turn be executed by a processor. In addition, the memory may store processing variables and constants for use by the processor.

The present invention is described in further detail below with reference to the attached drawing figures.

Fig. 1 is a flowchart illustrating a method for analog CSI feedback according to an embodiment of the present invention.

The method of the embodiment is mainly implemented by a base station and user equipment in a communication system. Preferably, the communication system is a 4G, 5G system or a subsequent upgrade system. The user equipment includes, but is not limited to, any user equipment capable of communicating with a base station, such as a tablet computer, a smart phone, a PDA, and the like. It should be noted that the base station, the user equipment and the communication system are only examples, and other existing or future base stations, user equipment and communication systems may be applicable to the present invention, and are included in the scope of the present invention and are included by reference.

The method according to the present embodiment includes step S101, step S102, step S103, and step S104.

In step S101, the ue obtains an analog CSI matrix corresponding to the ue.

Wherein the analog CSI matrix satisfies the following conditions:

X X^H＝D (1)

wherein, X represents the analog CSI matrix of R × K, R ≦ K, symbol "H" represents the conjugate transpose of the matrix, and D represents the diagonal matrix. Wherein, the elements on the opposite corners of the diagonal matrix D may be the same or different.

The step S101 is further described below in two preferred embodiments.

The first scheme is as follows:

the analog CSI matrix includes a third analog matrix corresponding to the estimated channel matrix, and the step S101 further includes: the user equipment performs Singular Value Decomposition (SVD) on an estimated channel matrix estimated by the user equipment to obtain corresponding main singular values (dominant singular values) and main right singular vectors (dominant right singular vectors), and obtains the third simulation matrix according to the main singular values and the main right singular vectors.

Wherein the main singular value represents a singular value dominating among singular values obtained by performing the SVD, and the main right singular vector represents a right singular vector dominating among right singular vectors obtained by performing the SVD.

Assuming that the base station has M antennas and the UE has N antennas, the UE may estimate a downlink estimated channel matrix of N × M based on a downlink reference signal from the base station, which is denoted as a, and perform SVD on a, thereby obtaining:

A＝USV^H(2)

wherein the left singular vector U is a matrix of N x J and satisfies U^HU is E, the singular value S is a diagonal matrix of J, the right singular vector V is a matrix of M J and satisfies V^HV ═ E, J is the rank of a, and E is the identity matrix. Since V is used by the base station to perform beamforming or interference suppression between different layers/UEs, U is used by the UE to perform beamforming or residual interference suppression, and S is used for power allocation between multiple streams to maximize link capacity, only matrices S and V are needed by the base station. Further consider that in practice S is usually controlled by only a small fraction of the dominant diagonal angles, if these are assumed to be the number of dominant diagonal angles I<J, then can be represented as follows:

wherein the dominant left singular vector

A matrix of N x I, representing the dominant left singular vector in U; principal singular value

A matrix of I x I, representing the diagonal of S that plays a dominant role; dominant right singular vector

The matrix, M × I, represents the dominant right singular vector in V. Thus, the third simulation matrix B may be represented as:

wherein, B is a matrix of I M.

Scheme II:

the analog CSI matrix includes a first analog matrix that needs to be transmitted to the base station in a long period mode and a second analog matrix that needs to be transmitted to the base station in a short period mode, and the step S101 further includes steps S1011 and S1012.

In step S1011, the ue obtains a main basis vector of a subspace of channel statistics by decomposing the channel covariance matrix, and determines the first simulation matrix according to the main basis vector.

Wherein the master basis vector is used to represent a dominant basis vector in space. Wherein the first simulation matrix is a combination matrix of the obtained basis vectors.

The present invention finds the following facts: the actual scattering geometry (scattering geometry) often makes the angle of departure of the channel path of the base station propagation limited, which results in high cross-correlation of the channels. In practice, the channel covariance matrix can be expressed as:

wherein F represents a covariance matrix, E (A)^HA) Is represented by A^HExpected value of A, g_iPrincipal basis vector of M1, L<M (M is the number of antennas of the base station), λ_iIs equal to g_iThe corresponding coefficients. Further, based on the above equation (5), it is possible to obtain:

A≈C[g₁...g_L]^H(6)

where C is a linear combination matrix. The first simulation matrix may be represented as:

G＝[g₁...g_L](7)

it should be noted that, since the basis vectors of the subspace are mainly determined by the spatial angles of the multipaths, the variation thereof is generally slow, and therefore, the first simulation matrix obtained by combining the principal basis vectors can be transmitted to the base station in a long-period simulation. Compared with the master basis vector, the elements in the linear combination matrix change faster based on doppler propagation, and therefore, a second analog matrix obtained subsequently from the linear combination matrix needs to be sent to the base station in a short-period mode.

In step S1012, the ue estimates a linear combination matrix corresponding to the first simulation matrix according to the downlink reference signal from the base station, performs singular value decomposition on the linear combination matrix to obtain a corresponding main singular value and a main right singular vector, and obtains the second simulation matrix according to the main singular value and the main right singular vector.

Wherein the downlink reference signal includes but is not limited to: beamformed CSI-RS signals, non-precoded CSI-RS signals, and the like. If the downlink reference signal is a wave beam forming CSI-RS signal (adopting g)₁，g₂，…，g_LAs a beam), the user equipment may estimate C as an equivalent channel matrix. If the downlink reference signal is an un-precoded CSI-RS signal, the ue may estimate C by considering the signal subspace spanned by G.

Wherein the elements in the linear combination matrix can be regarded as coefficients for the above-mentioned master basis vector.

Specifically, the user equipment estimates a linear combination matrix C corresponding to the first simulation matrix according to a downlink reference signal from the base station, performs singular value decomposition on C, and obtains corresponding main singular values and main right singular vectors based on the following formulas:

wherein U ', S ' and V ' are respectively a left singular vector, a singular value and a right singular vector obtained by executing SVD on C,

the left singular vectors are N x I ', the right singular vectors are I' x I ', and the right singular vectors are I' x L. Then the second analog matrix B' corresponding to C can be represented as:

wherein, B 'is a matrix of I'. times.L.

It should be noted that the operations of step S1011 and step S1012 described above are applicable to any antenna array.

In addition, as another preferred solution of this embodiment, the long-term feedback load can be further reduced and the feedback accuracy can be increased in a scenario where the base station employs a cross-polarized antenna array.

In this preferred embodiment, the step S1011 further includes: the user equipment averages channel covariance matrixes in two polarization directions, obtains a main basis vector of a subspace of channel statistics by decomposing a matrix obtained by performing averaging operation, and determines a first simulation matrix corresponding to the user equipment according to the main basis vector; the step S1012 further includes: and the user equipment estimates two linear combination matrixes respectively corresponding to the two polarization directions according to a downlink reference signal from the base station, combines the two linear combination matrixes, performs singular value decomposition on the combined matrixes to obtain corresponding main singular values and main right singular vectors, and obtains a second simulation matrix corresponding to the user equipment according to the main singular values and the main right singular vectors.

Specifically, the user equipment averages channel covariance matrices in two polarization directions, and obtains the following principal basis vectors by decomposing a matrix obtained by performing an averaging operation:

wherein,

the base vector is (M/2) × 1, and the user equipment can determine the first simulation matrix

The user equipment estimates two linear combination matrixes C1 and C2 respectively corresponding to the two polarization directions according to the downlink reference signals from the base station, combines C1 and C2 into C ', and then carries out singular value decomposition on C' based on the following formula to obtain a main singular value

And the main right singular vector

Wherein,

is the dominant left singular vector; thereafter, the user equipment may obtain a second simulation matrix based on the following formula

It should be noted that, the above examples are only for better illustrating the technical solutions of the present invention, and not for limiting the present invention, and those skilled in the art should understand that any implementation manner for obtaining the analog CSI matrix corresponding to the ue should be included in the scope of the present invention.

In step S102, the ue obtains the principal element information corresponding to the analog CSI matrix according to predetermined index information, and sends the principal element information to the base station.

The predetermined index information is pre-stored in the base station and the user equipment, and the predetermined index information includes any predetermined index information capable of indicating each element that needs to be sent to the base station (or does not need to be sent to the base station), such as an index of each element that needs to be sent to the base station in the matrix, an index of each element that does not need to be sent to the base station in the matrix, and the like. It should be noted that, for the matrix of R × K, the total number of elements that need not be transmitted to the base station is R (R-1)/2 (that is, the total number of elements that need to be transmitted to the base station is (2K-R +1) R/2), the elements that need not be transmitted to the base station are located in the (R-1) row of the matrix, and the number of elements that need not be transmitted to the base station is different in each of the (R-1) rows.

Note that, if the index of the element that is indicated by the predetermined index information and does not need to be transmitted to the base station is represented as: (a)₁，b_1,1)，(a₂，b_2,1)，(a₂，b_2,2)，…，(a_R-1，b_R-1,1)，…，(a_R-1，b_R-1,R-1) (ii) a The following conditions should be satisfied:

wherein, a_mIndicating that there are m elements that do not need to be sent to the base station, 1. ltoreq. m.ltoreq.R-1, b_m,nDenotes a_mThe nth element in the row is not required to be sent to the column of the base station, and n is more than or equal to 1 and less than or equal to m.

As an example, an analog CSI matrix of R × K is shown in fig. 5, where "×" indicates elements that do not need to be transmitted to the base station, "o" indicates elements that need to be transmitted to the base station, and the predetermined index information includes indexes corresponding to all of the "×". And as can be seen from fig. 5, only the first row elements need to be sent to the base station in its entirety, and 1 element in row 2 does not need to be sent, 2 elements in row 3 do not need to be sent, and so on, and R-1 elements in row R do not need to be sent.

The main element information corresponding to the analog CSI matrix includes but is not limited to: the main element information in the simulated CSI matrix, the main element information in other matrixes obtained based on the simulated CSI matrix, and the like. The primary element information is used to indicate the elements of the corresponding matrix whose dominant role is.

Specifically, the implementation manner of extracting, by the user equipment, the main element information in the analog CSI matrix according to the predetermined index information and sending the main element information to the base station includes but is not limited to:

1) the step S102 includes a step S1021. In step S1021, the ue extracts the principal element information in the analog CSI matrix according to the predetermined index information, and sends the principal element information to the base station.

As an example, the R × K analog CSI matrix is shown in fig. 5, and the predetermined index information includes indexes corresponding to elements that are not required to be sent to the base station, as follows: (a)₁，b_1,1)，(a₂，b_2,1)，(a₂，b_2,2)，…，(a_R-1，b_R-1,1)，…，(a_R-1，b_R-1,R-1) in step S1021, the ue extracts all the elements corresponding to "○" in the analog CSI matrix according to the predetermined index information, and transmits the extracted elements as the main element information to the base station.

Preferably, the step S1021 further comprises: the user equipment carries out permutation on the rows of the simulation CSI matrix according to the permutation matrix; and then, the user equipment extracts the main element information in the matrix obtained by replacement according to the preset index information and sends the main element information to the base station.

Specifically, the user equipment permutes the rows of the analog CSI matrix X based on the following formula:

X_p＝PX (13)

where P is a permutation matrix of R, X_pThe resulting matrix is permuted. And then, the user equipment extracts the main element information in the matrix obtained by replacement according to the preset index information and sends the main element information to the base station. Wherein, the user equipment extracts and replaces the index information according to the preset index informationThe implementation manner of the main element information in the matrix and sending the main element information to the base station is similar to that of the step S1021, and is not described again here.

It should be noted that X selected when the ue performs the sending operation_pI.e. the selected permutation matrix P, needs to be determined by:

where Y denotes a set of all predetermined permutation matrices, min denotes a minimum function, and Z { (a) }₁,b_1,1),(a₂,b_2,1),(a₂,b_2,2),…,(a_R-1,b_R-1,1),…,(a_R-1,b_R-1,R-1) The present preferred scheme can make the power of the unsent elements as small as possible, that is, make the power of the elements transmitted to the base station as large as possible, thereby enabling the base station to more reliably estimate (2K-R +1) R/2 elements transmitted to the base station to more reliably recover R (R-1)/2 elements unsent to the base station based on the elements transmitted to the base station.

2) The step S102 includes steps S1022 and S1023. In step S1022, the ue obtains a transformation matrix corresponding to the analog CSI matrix according to the predetermined index information, and transforms the analog CSI matrix based on the transformation matrix. In step S1023, the ue extracts all non-zero elements in the converted matrix and sends the non-zero elements to the base station as the information of the main elements corresponding to the analog CSI matrix. Wherein the conversion matrix is an orthogonal matrix.

Specifically, the predetermined index information indicates that the indexes corresponding to the elements that do not need to be transmitted to the base station are as follows: (a)₁，b_1,1)，(a₂，b_2,1)，(a₂，b_2,2)，…，(a_R-1，b_R-1,1)，…，(a_R-1，b_R-1,R-1). In step S1022, the user equipment first according to the b-th of X_R-1,1To b_R-1,R-1Column vectorCalculating the base vector s of the orthogonal complement space of the space₁And then s is₁Conjugate transpose of

A as a transformation matrix W_R-1A row vector; then according to s₁And b of X_R-2,1To b_R-2,R-2Base vector s of the orthogonal complement space of the space in which the column vector is calculated₂And then s is₂Conjugate transpose of

A as a transformation matrix W_R-2A row vector; and the like until all row vectors of W are obtained. The user equipment obtains the matrix after converting X based on the following formula

In that

The element corresponding to the index is a zero element. Thereafter, in step S1023, the user equipment extracts

And sending the non-zero elements to the base station as the main element information corresponding to the analog CSI matrix.

As an example, the user equipment may obtain a matrix structure similar to that shown in FIG. 5 by performing QR decomposition on a sub-matrix of X and obtaining a transformation matrix W in combination with predetermined index information

When FIG. 5 is considered as

wherein X is divided into X₁And X₂，X₁A sub-matrix of R, then X can be paired₁QR decomposition is performed to obtain an upper triangular matrix, and the transpose of the upper triangular matrix is taken as the conversion matrix W.

Compared to implementation 1), although the number of elements that require feedback is the same, implementation 2) has the following advantages: a) since the power is concentrated on (2K-R +1) R/2 transmission symbols, the CSI estimate SINR is better than implementation 1; b) since all channel coefficients are estimated independently, there is no propagation effect of estimation errors. Therefore, implementation 2) has a higher CSI feedback quality.

As another preferred scheme of step S102, when the analog CSI matrix includes a first analog matrix that needs to be sent to the base station in a long-period mode and a second analog matrix that needs to be sent to the base station in a short period, the ue obtains the main element information corresponding to the first analog matrix according to the predetermined index information, and sends the main element information corresponding to the first analog matrix to the base station in the long-period mode; and acquiring main element information corresponding to the second simulation matrix according to the preset index information, and sending the main element information corresponding to the second simulation matrix to a base station in a short-period mode.

It should be noted that the long period mode refers to that the user equipment performs corresponding transmission operations at a longer period, and the short period mode refers to that the user equipment performs corresponding transmission operations at a shorter period. It should be understood by those skilled in the art that there is no strict order relationship between the operations for obtaining the first simulation matrix and obtaining the second simulation matrix, and there is no strict order relationship between the operations for sending the principal element information corresponding to the first simulation matrix and the operations for sending the principal element information corresponding to the second simulation matrix. For example, the user equipment is arranged at intervals t₁Executing the operation of obtaining the first simulation matrix, and then executing the sending of the main element information corresponding to the first simulation matrix; and the user equipment is arranged at intervals t₂Just perform and obtainOperation of the second simulation matrix and subsequent execution of sending of principal element information corresponding to the second simulation matrix, where t₁>t₂。

The preferred scheme realizes the analog CSI feedback by combining the long period mode and the short period mode, can more effectively utilize the feedback channel, and can reduce the feedback load to a greater extent.

It should be noted that, the above examples are only for better illustrating the technical solutions of the present invention, and not for limiting the present invention, and those skilled in the art should understand that any implementation manner of obtaining the principal element information corresponding to the analog CSI matrix according to the predetermined index information and sending the principal element information to the base station should be included in the scope of the present invention.

In step S103, the base station receives the principal element information corresponding to the analog CSI matrix from the user equipment.

In step S104, the base station obtains the analog CSI matrix according to predetermined index information and the main element information.

As a preferred scheme, the main element information is extracted from the analog CSI matrix, and the base station calculates other elements in the analog CSI matrix except for the main element information according to predetermined index information and the main element information to obtain the analog CSI matrix.

In addition, X is represented by

Where the symbol "T" represents the transpose of the matrix, it can be seen that X satisfies the following relationship based on the above formula (1):

x_r+1X(1:r,:)^H＝0_1*r(16)

wherein x is_r+1Represents the r +1 th row of X, and X (1: r:) represents the first to r-th rows of X. Further obtainable are:

X(1:r,1:r)^*x_r+1(1:r)^T＝-X(1:r,r+1:K)^*x_r+1(r+1:K)^T(17)

wherein,x (1: r ) is composed of first to r-th rows and first to r-th columns of X, X_r+1(1: r) consists of elements 1 to r in row r +1, the "x" in the upper right corner representing the conjugation. As shown in formula (17), when X (1: r:) and X_r+1(r +1: K) is known, then x can be calculated_r+1(1:r)。

As an example, in step S103, the base station receives main element information from the user equipment, the main element information including elements of the positions where all "∘" is located in fig. 5; in step S104, the base station determines an element index that is not transmitted to the base station based on predetermined index information, and restores the element that is not transmitted to the base station based on the following formula:

where the horizontal line below indicates that the matrix is unknown. That is, for the analog CSI matrix shown in FIG. 5, the base station first bases on the known first row vectors X (1:) and X₂(2: K) restoring the first element x in the second row₂(1) (ii) a Next, the base station obtains all elements of X (1:2,) and knows X from X (1:2,) and₃(3: K) recovery of x₃(1:2), and so on until all the elements at "×" shown in fig. 5 are restored.

It should be noted that, when the main element information is extracted from the pair X_pThe base station recovers X based on the preferred scheme_pThen, the X_pCan be directly viewed as an analog CSI matrix corresponding to the user equipment.

As another preferred scheme, the main element information includes all non-zero elements in a matrix obtained by converting the analog CSI matrix, and the base station determines the matrix obtained by converting the analog CSI matrix according to predetermined index information and the main element information, wherein other elements except the main element information in the converted matrix are zero; and then, the base station carries out singular value decomposition on the converted matrix to obtain a singular value and a right singular vector corresponding to the converted matrix, and obtains the simulation CSI matrix according to the singular value and the right singular vector.

The base station sets all elements which are not sent to the base station to be zero according to the preset index information, and therefore the matrix obtained after X is converted is obtained

It should be noted that, based on equation (1), X can be found to be represented as:

X＝D^1/2Q (21)

where Q is an orthogonal matrix, since D is a diagonal matrix, WD can be found based on the formula (21) and the formula (15)^1/2Q is precisely

SVD of (1), then

Executing SVD:

wherein,

respectively obtaining a left singular vector, a singular value and a right singular vector by executing SVD; thus, it is possible to obtain:

preferably, when the analog CSI matrix includes a first analog matrix transmitted to the base station in a long period mode and a second analog matrix transmitted to the base station in a short period mode. The method further comprises the following steps: and the base station obtains a third analog matrix corresponding to the user equipment according to the first analog matrix and the second analog matrix.

For example, the analog CSI matrix includes the first analog matrix G and the second analog matrix B' described above, and the base station may obtain the third analog matrix B based on the following formula:

B＝B'G^H(24)

for another example, in a scenario where the base station employs a cross-polarized antenna array, the analog CSI matrix includes the first analog matrix

And a second analog matrix

The base station may obtain a third simulation matrix B based on the following equation:

it should be noted that, the above examples are only for better illustrating the technical solutions of the present invention, and not for limiting the present invention, and those skilled in the art should understand that any implementation manner of obtaining the analog CSI matrix according to the predetermined index information and the main element information should be included in the scope of the present invention.

Although the analog feedback proposed so far may be a simple concept, it still faces many problems in practical applications, such as: a) for large antenna arrays, the overhead of analog feedback may also be significant; b) how to ensure that the base station can recover the CSI as much as possible.

According to the scheme of the embodiment, the feedback overhead can be reduced to a great extent by sending the main element information corresponding to the analog CSI matrix to the base station, and better CSI recovery quality can be realized at the base station due to the fact that the power is concentrated on the main element information; in addition, the feedback process is divided into two stages, the main element information corresponding to the first simulation matrix is sent in a long period mode, and the main element information corresponding to the second simulation matrix is sent in a short period mode, so that the feedback overhead can be further reduced; furthermore, byWhen the analog CSI matrix satisfies X X^HThe condition of D can be directly used for further precoding and beamforming, thus simplifying the implementation at the base station.

Fig. 2 is a flowchart illustrating a method for analog CSI feedback according to another embodiment of the present invention. The method according to the present embodiment includes step S201, step S202, step S203, step S204, and step S205.

In step S201, the ue obtains a main basis vector of a subspace of channel statistics by decomposing the channel covariance matrix, and determines a first simulation matrix corresponding to the ue according to the main basis vector.

The implementation manner of step S201 is the same as or similar to the implementation manner of step S1011, and is not described herein again.

In step S202, the ue estimates a linear combination matrix corresponding to the first analog matrix according to a downlink reference signal from the base station.

The implementation of the ue estimating the linear combination matrix corresponding to the first analog matrix according to the downlink reference signal from the base station has been described in detail in the foregoing embodiments, and is not described herein again.

In step S203, the ue sends the first analog matrix to the base station in a long period mode, and sends the associated feedback information corresponding to the linear combination matrix to the base station in a short period mode.

Wherein the associated feedback information includes any information determined based on the linear combination matrix that needs to be transmitted to the base station in the short period mode.

For example, the ue directly uses the linear combination matrix C as the associated feedback information, and sends the first analog matrix G to the base station in the long period mode, and sends C to the base station in the short period mode.

As a preferable scheme, the step S203 further includes: the user equipment carries out singular value decomposition on the linear combination matrix to obtain corresponding main singular values and main right singular vectors, and obtains a second simulation matrix corresponding to the linear combination matrix according to the main singular values and the main right singular vectors; and the user equipment sends the first simulation matrix to the base station in a long period mode, and sends the second simulation matrix to the base station in a short period mode as the associated feedback information.

The implementation manner of the ue obtaining the second simulation matrix has been described in detail in the foregoing embodiments, and is not described herein again.

For example, the user equipment transmits the first analog matrix G to the base station in a long periodic pattern, and transmits the second analog matrix B' to the base station in a short periodic pattern.

It should be noted that, preferably, in a scenario where the base station employs a cross-polarized antenna array, the first analog matrix is the above-mentioned one

The associated feedback information is the above-mentioned

The user equipment will be in long period mode

Transmitting to the base station in short period mode

And sending to the base station.

Compared with the scheme of directly using the linear combination matrix as the associated feedback information, the preferred scheme can further save the feedback symbol quantity.

It should be noted that, the above examples are only for better illustrating the technical solutions of the present invention, and not for limiting the present invention, and those skilled in the art should understand that any implementation manner in which the ue sends the first analog matrix to the base station in the long period mode and sends the associated feedback information corresponding to the linear combination matrix to the base station in the short period mode should be included in the scope of the present invention.

In step S204, the base station receives a first analog matrix sent by the ue to the base station in a long period mode and associated feedback information corresponding to the linear combination matrix sent to the base station in a short period mode.

In step S205, the base station obtains CSI feedback information corresponding to the ue according to the first simulation matrix and the associated feedback information.

For example, the base station obtains an approximate a from the received first analog matrix G and linear combination matrix C, in combination with equation (6).

Preferably, the associated feedback information is a second analog matrix corresponding to the user equipment.

For example, the base station obtains (24) a third simulation matrix B corresponding to the user equipment according to the received first simulation matrix G and the second simulation matrix B' and by combining the formula.

For another example, in a scenario where the base station employs a cross-polarized antenna array, the base station bases on the received first analog matrix

And a second analog matrix

And obtaining (25) a third simulation matrix B corresponding to the user equipment in combination with the formula.

It should be noted that, the foregoing examples are only for better illustrating the technical solutions of the present invention, and are not limiting to the present invention, and those skilled in the art should understand that any implementation manner for obtaining the CSI feedback information corresponding to the ue by the base station according to the first analog matrix and the associated feedback information should be included in the scope of the present invention.

Compared with the scheme of directly sending the estimated channel matrix in the prior art, in the embodiment, the first analog matrix is sent in the long-period mode, and the associated feedback information corresponding to the linear combination matrix is sent in the short-period mode, so that the feedback load can be reduced, and the base station can be ensured to reliably obtain the CSI feedback information corresponding to the user equipment.

Fig. 3 is a schematic structural diagram of a system for analog CSI feedback according to an embodiment of the present invention. The system comprises a base station and user equipment. The user equipment comprises a first device for analog CSI feedback, the first device comprises a first obtainingdevice 101 and a first sending device 102; the base station comprises second means for obtaining an analog CSI matrix corresponding to the user equipment, the second means comprising first receiving means 103 and second obtainingmeans 104.

The first obtainingdevice 101 of the user equipment obtains the analog CSI matrix corresponding to the user equipment.

Wherein the analog CSI matrix satisfies the following conditions:

X X^H＝D (1)

wherein, X represents the analog CSI matrix of R × K, R ≦ K, symbol "H" represents the conjugate transpose of the matrix, and D represents the diagonal matrix. Wherein, the elements on the opposite corners of the diagonal matrix D may be the same or different.

The first obtainingmeans 101 is further described below in two preferred embodiments.

The first scheme is as follows:

the analog CSI matrix comprises a third analog matrix corresponding to the estimated channel matrix, and the first obtaining means 101 further comprises a fifth sub-obtaining means (not shown). The fifth sub-obtaining device performs Singular Value Decomposition (SVD) on the estimated channel matrix estimated by the ue to obtain corresponding main Singular values (dominant Singular values) and main right Singular vectors (dominant right Singular vectors), and obtains the third simulation matrix according to the main Singular values and the main right Singular vectors.

Wherein the main singular value represents a singular value dominating among singular values obtained by performing the SVD, and the main right singular vector represents a right singular vector dominating among right singular vectors obtained by performing the SVD.

Assuming that the base station has M antennas and the UE has N antennas, the UE may estimate to obtain a downlink estimated channel matrix of N × M based on a downlink reference signal from the base station, which is denoted as a, and the fifth sub-obtaining device performs SVD on a, so as to obtain:

A＝USV^H(2)

wherein the left singular vector U is a matrix of N x J and satisfies U^HU is E, the singular value S is a diagonal matrix of J, the right singular vector V is a matrix of M J and satisfies V^HV ═ E, J is the rank of a, and E is the identity matrix. Since V is used by the base station to perform beamforming or interference suppression between different layers/UEs, U is used by the UE to perform beamforming or residual interference suppression, and S is used for power allocation between multiple streams to maximize link capacity, only matrices S and V are needed by the base station. Further consider that in practice S is usually controlled by only a small fraction of the dominant diagonal angles, if these are assumed to be the number of dominant diagonal angles I<J, then can be represented as follows:

wherein the dominant left singular vector

A matrix of N x I, representing the dominant left singular vector in U; principal singular value

A matrix of I x I, representing the diagonal of S that plays a dominant role; dominant right singular vector

The matrix, M × I, represents the dominant right singular vector in V. Thus, the third simulation matrix B may be represented as:

wherein, B is a matrix of I M.

Scheme II:

the analog CSI matrix includes a first analog matrix to be transmitted to the base station in a long period mode and a second analog matrix to be transmitted to the base station in a short period mode, and the first obtaining means 101 further includes a first sub-obtaining means (not shown) and a second sub-obtaining means (not shown).

The first sub-obtaining means obtains a principal basis vector of a subspace of channel statistics by decomposing a channel covariance matrix, and determines the first simulation matrix from the principal basis vector.

Wherein the master basis vector is used to represent a dominant basis vector in space. Wherein the first simulation matrix is a combination matrix of the obtained basis vectors.

The present invention finds the following facts: the actual scattering geometry (scattering geometry) often makes the angle of departure of the channel path of the base station propagation limited, which results in high cross-correlation of the channels. In practice, the channel covariance matrix can be expressed as:

wherein F represents a covariance matrix, E (A)^HA) Is represented by A^HExpected value of A, g_iPrincipal basis vector of M1, L<M (M is the number of antennas of the base station), λ_iIs equal to g_iThe corresponding coefficients. Further, based on the above equation (5), it is possible to obtain:

A≈C[g₁...g_L]^H(6)

where C is a linear combination matrix. The first simulation matrix may be represented as:

G＝[g₁...g_L](7)

it should be noted that, since the basis vectors of the subspace are mainly determined by the spatial angles of the multipaths, the variation thereof is generally slow, and therefore, the first simulation matrix obtained by combining the principal basis vectors can be transmitted to the base station in a long-period simulation. Compared with the master basis vector, the elements in the linear combination matrix change faster based on doppler propagation, and therefore, a second analog matrix obtained subsequently from the linear combination matrix needs to be sent to the base station in a short-period mode.

The second sub-obtaining device estimates a linear combination matrix corresponding to the first simulation matrix according to a downlink reference signal from a base station, performs singular value decomposition on the linear combination matrix to obtain a corresponding main singular value and a main right singular vector, and obtains the second simulation matrix according to the main singular value and the main right singular vector.

Wherein the downlink reference signal includes but is not limited to: beamformed CSI-RS signals, non-precoded CSI-RS signals, and the like. If the downlink reference signal is a wave beam forming CSI-RS signal (adopting g)₁，g₂，…，g_LAs a beam), the user equipment may estimate C as an equivalent channel matrix. If the downlink reference signal is an un-precoded CSI-RS signal, the ue may estimate C by considering the signal subspace spanned by G.

Wherein the elements in the linear combination matrix can be regarded as coefficients for the above-mentioned master basis vector.

Specifically, the second sub-obtaining means estimates a linear combination matrix C corresponding to the first simulation matrix from the downlink reference signal from the base station, performs singular value decomposition on C, and obtains corresponding main singular values and main right singular vectors based on the following formulas:

wherein U ', S ' and V ' are respectively a left singular vector, a singular value and a right singular vector obtained by executing SVD on C,

the left singular vectors are N x I ', the right singular vectors are I' x I ', and the right singular vectors are I' x L. Then the second analog matrix B' corresponding to C can be represented as:

wherein, B 'is a matrix of I'. times.L.

It should be noted that the operations performed by the first sub-obtaining means and the second sub-obtaining means are applicable to any antenna array.

In addition, as another preferred solution of this embodiment, the long-term feedback load can be further reduced and the feedback accuracy can be increased in a scenario where the base station employs a cross-polarized antenna array.

In this preferred embodiment, the first sub-obtaining device further includes a third sub-obtaining device (not shown), and the second sub-obtaining device further includes a fourth sub-obtaining device (not shown). The third sub-obtaining device averages the channel covariance matrixes in the two polarization directions, obtains a main basis vector of a subspace of channel statistics by decomposing a matrix obtained by performing averaging operation, and determines a first simulation matrix corresponding to the user equipment according to the main basis vector. The fourth sub-obtaining device estimates two linear combination matrixes respectively corresponding to the two polarization directions according to a downlink reference signal from the base station, combines the two linear combination matrixes, performs singular value decomposition on the combined matrixes to obtain corresponding main singular values and main right singular vectors, and obtains a second simulation matrix corresponding to the user equipment according to the main singular values and the main right singular vectors.

Specifically, the third sub-obtaining means averages the channel covariance matrices in the two polarization directions, and obtains the following principal basis vectors by decomposing the matrix obtained by performing the averaging operation:

wherein,

the base vector is (M/2) × 1, and the user equipment can determine the first simulation matrix

The fourth sub-obtaining means estimates two linear combination matrices C1 and C2 respectively corresponding to the two polarization directions from the downlink reference signal from the base station, combines C1 and C2 into C ', and then performs singular value decomposition on C' based on the following formula to obtain a main singular value

And the main right singular vector

Wherein,

is the dominant left singular vector; thereafter, the user equipment may obtain a second simulation matrix based on the following formula

It should be noted that, the above examples are only for better illustrating the technical solutions of the present invention, and not for limiting the present invention, and those skilled in the art should understand that any implementation manner for obtaining the analog CSI matrix corresponding to the ue should be included in the scope of the present invention.

The first sending device 102 obtains the principal element information corresponding to the analog CSI matrix according to the predetermined index information, and sends the principal element information to the base station.

The predetermined index information is pre-stored in the base station and the user equipment, and the predetermined index information includes any predetermined index information capable of indicating each element that needs to be sent to the base station (or does not need to be sent to the base station), such as an index of each element that needs to be sent to the base station in the matrix, an index of each element that does not need to be sent to the base station in the matrix, and the like. It should be noted that, for the matrix of R × K, the total number of elements that need not be transmitted to the base station is R (R-1)/2 (that is, the total number of elements that need to be transmitted to the base station is (2K-R +1) R/2), the elements that need not be transmitted to the base station are located in the (R-1) row of the matrix, and the number of elements that need not be transmitted to the base station is different in each of the (R-1) rows.

Note that, if the index of the element that is indicated by the predetermined index information and does not need to be transmitted to the base station is represented as: (a)₁，b_1,1)，(a₂，b_2,1)，(a₂，b_2,2)，…，(a_R-1，b_R-1,1)，…，(a_R-1，b_R-1,R-1) (ii) a The following conditions should be satisfied:

wherein, a_mIndex of row which indicates that m elements do not need to be transmitted to base station, 1 ≦ m ≦ R-1, b_m,nDenotes a_mThe nth column in the indicated row, where the element that does not need to be sent to the base station is located, is 1 ≦ n ≦ m.

As an example, an analog CSI matrix of R × K is shown in fig. 5, where "×" indicates elements that do not need to be transmitted to the base station, "o" indicates elements that need to be transmitted to the base station, and the predetermined index information includes indexes corresponding to all of the "×". And as can be seen from fig. 5, only the first row elements need to be sent to the base station in its entirety, and 1 element in row 2 does not need to be sent, 2 elements in row 3 do not need to be sent, and so on, and R-1 elements in row R do not need to be sent.

The main element information corresponding to the analog CSI matrix includes but is not limited to: the main element information in the simulated CSI matrix, the main element information in other matrixes obtained based on the simulated CSI matrix, and the like. The primary element information is used to indicate the elements of the corresponding matrix whose dominant role is.

Specifically, the implementation manner of the first sending apparatus 102 extracting the main element information in the analog CSI matrix according to the predetermined index information and sending the main element information to the base station includes, but is not limited to:

1) the first transmitting apparatus 102 includes a first sub-transmitting apparatus (not shown). And the first sub-transmitting device extracts the main element information in the analog CSI matrix according to the preset index information and transmits the main element information to the base station.

As an example, the R × K analog CSI matrix is shown in fig. 5, and the predetermined index information includes indexes corresponding to elements that are not required to be sent to the base station, as follows: (a)₁，b_1,1)，(a₂，b_2,1)，(a₂，b_2,2)，…，(a_R-1，b_R-1,1)，…，(a_R-1，b_R-1,R-1) the first sub-transmitting device extracts elements corresponding to all '○' in the analog CSI matrix according to the preset index information and transmits the extracted elements as main element information to the base station.

Preferably, the first sub-transmitting means further comprises row permuting means (not shown) and second sub-transmitting means (not shown). The row replacement device replaces rows of the analog CSI matrix according to the replacement matrix; then, the second sub-transmitting device extracts the main element information in the matrix obtained by the permutation according to the predetermined index information, and transmits the main element information to the base station.

Specifically, the row permutation device permutes the rows of the analog CSI matrix X based on the following formula:

X_p＝PX (13)

where P is a permutation matrix of R, X_pThe resulting matrix is permuted. Then, the user equipment extracts the moment obtained by the replacement according to the preset index informationAnd main element information in the array is sent to the base station. The implementation manner of the second sub-sending device is similar to that of the first sub-sending device, and is not described herein again.

It should be noted that X selected when the second sub-transmitting apparatus performs the transmitting operation_pI.e. the selected permutation matrix P, needs to be determined by:

where Y denotes a set of all predetermined permutation matrices, min denotes a minimum function, and Z { (a) }₁,b_1,1),(a₂,b_2,1),(a₂,b_2,2),…,(a_R-1,b_R-1,1),…,(a_R-1,b_R-1,R-1)}. As can be seen from the above equation (14), the preferred embodiment can make the power of the elements not transmitted as small as possible, that is, make the power of the elements transmitted to the base station as large as possible, thereby enabling the base station to more reliably estimate (2K-R +1) R/2 elements transmitted to the base station to more reliably recover R (R-1)/2 elements not transmitted to the base station based on the elements transmitted to the base station.

2) The first sending device 102 includes a converting device (not shown) and a third sub-sending device (not shown). The conversion device obtains a conversion matrix corresponding to the analog CSI matrix according to the preset index information, and converts the analog CSI matrix based on the conversion matrix. And the third sub-transmitting device extracts all non-zero elements in the converted matrix and transmits the non-zero elements to the base station as main element information corresponding to the analog CSI matrix. Wherein the conversion matrix is an orthogonal matrix.

Specifically, the predetermined index information indicates that the indexes corresponding to the elements that do not need to be transmitted to the base station are as follows: (a)₁，b_1,1)，(a₂，b_2,1)，(a₂，b_2,2)，…，(a_R-1，b_R-1,1)，…，(a_R-1，b_R-1,R-1). Conversion deviceFirst according to b of X_R-1,1To b_R-1,R-1Base vector s of the orthogonal complement space of the space in which the column vector is calculated₁And then s is₁Conjugate transpose of

A as a transformation matrix W_R-1A row vector; then according to s₁And b of X_R-2,1To b_R-2,R-2Base vector s of the orthogonal complement space of the space in which the column vector is calculated₂And then s is₂Conjugate transpose of

A as a transformation matrix W_R-2A row vector; and the like until all row vectors of W are obtained. The conversion means obtains a matrix after converting X based on the following formula

In that

The element corresponding to the index is a zero element. Thereafter, the third sub-transmitting apparatus extracts

And sending the non-zero elements to the base station as the main element information corresponding to the analog CSI matrix.

As an example, the conversion apparatus may obtain a matrix structure similar to that shown in FIG. 5 by performing QR decomposition on a sub-matrix of X and obtaining a conversion matrix W in conjunction with predetermined index information

When FIG. 5 is taken as

wherein X is divided into X₁And X₂，X₁A sub-matrix of R, then X can be paired₁QR decomposition is performed to obtain an upper triangular matrix, and the transpose of the upper triangular matrix is taken as the conversion matrix W.

Compared to implementation 1), although the number of elements that require feedback is the same, implementation 2) has the following advantages: a) since the power is concentrated on (2K-R +1) R/2 transmission symbols, the CSI estimate SINR is better than implementation 1; b) since all channel coefficients are estimated independently, there is no propagation effect of estimation errors. Therefore, implementation 2) has a higher CSI feedback quality.

As another preferable mode of the first transmitting apparatus 102, the first transmitting apparatus 102 includes a fourth sub-transmitting apparatus (not shown) and a fifth sub-transmitting apparatus (not shown). When the analog CSI matrix comprises a first analog matrix and a second analog matrix, the fourth sub-transmitting device obtains main element information corresponding to the first analog matrix according to the preset index information and transmits the main element information to the base station in a long-period mode; and the fifth sub-transmitting device acquires the main element information corresponding to the second analog matrix according to the preset index information and transmits the main element information to the base station in a short period mode.

It should be noted that the long period mode refers to that the user equipment performs corresponding transmission operations at a longer period, and the short period mode refers to that the user equipment performs corresponding transmission operations at a shorter period. It should be understood by those skilled in the art that there is no strict order relationship between the operations for obtaining the first simulation matrix and obtaining the second simulation matrix, and there is no strict order relationship between the operations for sending the principal element information corresponding to the first simulation matrix and the operations for sending the principal element information corresponding to the second simulation matrix. For example, the user equipment is arranged at intervals t₁Executing the operation of obtaining the first simulation matrix, and then executing the sending of the main element information corresponding to the first simulation matrix; and useUser equipment every time t₂An operation of obtaining a second simulation matrix is performed and then transmission of principal element information corresponding to the second simulation matrix is performed, wherein t₁>t₂。

The preferred scheme realizes the analog CSI feedback by combining the long period mode and the short period mode, can more effectively utilize the feedback channel, and can reduce the feedback load to a greater extent.

It should be noted that, the above examples are only for better illustrating the technical solutions of the present invention, and not for limiting the present invention, and those skilled in the art should understand that any implementation manner of obtaining the principal element information corresponding to the analog CSI matrix according to the predetermined index information and sending the principal element information to the base station should be included in the scope of the present invention.

The first receiving means 103 of the base station receives the principal element information corresponding to the analog CSI matrix from the user equipment.

The second obtainingdevice 104 of the base station obtains the analog CSI matrix according to the predetermined index information and the main element information.

Preferably, the main element information is extracted from the analog CSI matrix, and the second obtaining means 104 includes a calculating means (not shown). And the calculating device calculates other elements except the main element information in the analog CSI matrix according to preset index information and the main element information so as to obtain the analog CSI matrix.

In addition, X is represented by

Where the symbol "T" represents the transpose of the matrix, it can be seen that X satisfies the following relationship based on the above formula (1):

x_r+1X(1:r,:)^H＝0_1*r(16)

wherein x is_r+1Represents the r +1 th row of X, and X (1: r:) represents the first to r-th rows of X. Further obtainable are:

X(1:r,1:r)^*x_r+1(¹:r)^T＝-X(1:r,r+1:K)^*x_r+1(r+1:K)^T(17)

wherein X (1: r ) is composed of first row to r-th row and first column to r-th column of X, X_r+1(1: r) consists of elements 1 to r in row r +1, the "x" in the upper right corner representing the conjugation. As shown in formula (17), when X (1: r:) and X_r+1(r +1: K) is known, then x can be calculated_r+1(1:r)。

As an example, the first receiving device 103 receives the main element information from the ue, which includes the elements of the positions of all "∘" in fig. 5; the calculation means determines an element index that is not transmitted to the base station based on predetermined index information, and restores the element that is not transmitted to the base station based on the following formula:

where the horizontal line below indicates that the matrix is unknown. That is, for the analog CSI matrix shown in FIG. 5, the computing device first bases on the known first row vectors X (1:) and X₂(2: K) restoring the first element x in the second row₂(1) (ii) a Next, the computing device obtains all elements of X (1:2,) and from X (1:2,) and the known X₃(3: K) recovery of x₃(1:2), and so on until all the elements at "×" shown in fig. 5 are restored.

It should be noted that, when the main element information is extracted from the pair X_pThe computing device then recovers X based on the preferred scheme_pThen, the X_pCan be directly used as an analog CSI matrix corresponding to the user equipment.

As another preferred solution, the main element information includes all non-zero elements in the matrix after the analog CSI matrix is converted, and the second obtaining means includes a determining means (not shown) and a sixth sub-obtaining means (not shown). The determining device determines a matrix obtained after converting the analog CSI according to preset index information and the main element information, wherein other elements except the main element information in the converted matrix are zero; then, the sixth sub-obtaining device performs singular value decomposition on the converted matrix to obtain singular values and right singular vectors corresponding to the converted matrix, and obtains the simulated CSI matrix according to the singular values and the right singular vectors.

Wherein the determining means sets all elements not transmitted to the base station to zero according to predetermined index information, thereby obtaining a matrix after converting X

It should be noted that, based on equation (1), X can be found to be represented as:

X＝D^1/2Q (21)

where Q is an orthogonal matrix, since D is a diagonal matrix, WD can be found based on the formula (21) and the formula (15)^1/2Q is precisely

The sixth sub-obtaining device pair

Executing SVD:

wherein,

respectively obtaining a left singular vector, a singular value and a right singular vector by executing SVD; thus, it is possible to obtain:

preferably, when the analog CSI matrix includes a first analog matrix transmitted to the base station in a long period mode and a second analog matrix transmitted to the base station in a short period mode. The second apparatus further comprises a seventh sub-obtaining means (not shown). The seventh sub-obtaining device obtains a third analog matrix corresponding to the user equipment according to the first analog matrix and the second analog matrix.

For example, the analog CSI matrix includes the first analog matrix G and the second analog matrix B' described above, and the seventh sub-obtaining means may obtain the third analog matrix B based on the following formula:

B＝B'G^H(24)

for another example, in a scenario where the base station employs a cross-polarized antenna array, the analog CSI matrix includes the first analog matrix

And a second analog matrix

The seventh sub-obtaining means may obtain the third simulation matrix B based on the following equation:

it should be noted that, the above examples are only for better illustrating the technical solutions of the present invention, and not for limiting the present invention, and those skilled in the art should understand that any implementation manner of obtaining the analog CSI matrix according to the predetermined index information and the main element information should be included in the scope of the present invention.

Although the analog feedback proposed so far may be a simple concept, it still faces many problems in practical applications, such as: a) for large antenna arrays, the overhead of analog feedback may also be significant; b) how to ensure that the base station can recover the CSI as much as possible.

According to the scheme of the embodiment, the feedback overhead can be reduced to a great extent by sending the main element information corresponding to the analog CSI matrix to the base station, and better CSI recovery quality can be realized at the base station due to the fact that the power is concentrated on the main element information; and, by dividing the feedback process into two stages, transmitting and in a long period modeThe main element information corresponding to the first analog matrix is sent in a short period mode, so that the feedback overhead can be further reduced; in addition, since the analog CSI matrix satisfies X X^HThe condition of D can be directly used for further precoding and beamforming, thus simplifying the implementation at the base station.

Fig. 4 is a schematic structural diagram of a system for analog CSI feedback according to another embodiment of the present invention. The system comprises a base station and user equipment. The user equipment comprises a third means for analog CSI feedback, which comprises a third obtaining means 201, an estimating means 202 and a second transmitting means 203; the base station comprises a fourth means for obtaining CSI feedback information corresponding to the user equipment, and the fourth means comprises a second receiving means 204 and a fourth obtainingmeans 205.

The third obtaining means 201 obtains a main basis vector of a subspace of channel statistics by decomposing the channel covariance matrix, and determines a first analog matrix corresponding to the user equipment according to the main basis vector.

The implementation manner of the third obtaining means 201 is the same as or similar to the implementation manner of the first sub-obtaining means, and is not described herein again.

The estimation means 202 estimates a linear combination matrix corresponding to the first analog matrix according to a downlink reference signal from the base station.

The implementation of the estimation device 202 for estimating the linear combination matrix corresponding to the first analog matrix according to the downlink reference signal from the base station has been described in detail in the foregoing embodiments, and is not described herein again.

Thesecond sending device 203 sends the first analog matrix to a base station in a long period mode, and sends the associated feedback information corresponding to the linear combination matrix to the base station in a short period mode.

Wherein the associated feedback information includes any information determined based on the linear combination matrix that needs to be transmitted to the base station in the short period mode.

For example, thesecond transmitting device 203 directly uses the linear combination matrix C as the associated feedback information, and the ue transmits the first analog matrix G to the base station in the long period mode and transmits C to the base station in the short period mode.

Preferably, thesecond sending device 203 further comprises a fifth obtaining device (not shown) and a third sending device (not shown). A fifth obtaining device performs singular value decomposition on the linear combination matrix to obtain corresponding main singular values and main right singular vectors, and obtains a second simulation matrix corresponding to the linear combination matrix according to the main singular values and the main right singular vectors; the third transmitting device transmits the first analog matrix to the base station in a long cycle mode, and transmits the second analog matrix to the base station in a short cycle mode as the associated feedback information.

The implementation manner of the fifth obtaining device for obtaining the second analog matrix is similar to that of the second sub-obtaining device, and is not described herein again.

For example, the third transmitting device transmits the first analog matrix G to the base station in a long cycle mode, and transmits the second analog matrix B' to the base station in a short cycle mode.

It should be noted that, preferably, in a scenario where the base station employs a cross-polarized antenna array, the first analog matrix is the above-mentioned one

The associated feedback information is the above-mentioned

The third transmitting device will transmit in long period mode

Transmitting to the base station in short period mode

And sending to the base station.

Compared with the scheme of directly using the linear combination matrix as the associated feedback information, the preferred scheme can further save the feedback symbol quantity.

It should be noted that, the above examples are only for better illustrating the technical solutions of the present invention, and not for limiting the present invention, and those skilled in the art should understand that any implementation manner in which the ue sends the first analog matrix to the base station in the long period mode and sends the associated feedback information corresponding to the linear combination matrix to the base station in the short period mode should be included in the scope of the present invention.

The second receiving means 204 of the base station receives the first analog matrix sent by the ue to the base station in the long period mode and the associated feedback information corresponding to the linear combination matrix sent to the base station in the short period mode.

The fourth obtainingdevice 205 of the base station obtains CSI feedback information corresponding to the ue according to the first analog matrix and the associated feedback information.

For example, the fourth obtaining means 205 obtains an approximate a from the first analog matrix G and the linear combination matrix C in combination with equation (6).

Preferably, the associated feedback information is a second analog matrix corresponding to the user equipment.

For example, the fourth obtaining means 205 obtains (24) a third simulation matrix B corresponding to the user equipment according to the first simulation matrix G and the second simulation matrix B' and by combining the formula.

For another example, in a scenario where the base station employs a cross-polarized antenna array, the fourth obtainingdevice 205 obtains the first analog matrix according to the first analog matrix

And a second analog matrix

And obtaining (25) a third simulation matrix B corresponding to the user equipment in combination with the formula.

It should be noted that, the foregoing examples are only for better illustrating the technical solutions of the present invention, and are not limiting to the present invention, and those skilled in the art should understand that any implementation manner for obtaining the CSI feedback information corresponding to the ue by the base station according to the first analog matrix and the associated feedback information should be included in the scope of the present invention.

Compared with the scheme of directly sending the estimated channel matrix in the prior art, in the embodiment, the first analog matrix is sent in the long-period mode, and the associated feedback information corresponding to the linear combination matrix is sent in the short-period mode, so that the feedback load can be reduced, and the base station can be ensured to reliably obtain the CSI feedback information corresponding to the user equipment.

It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned. Furthermore, it is obvious that the word "comprising" does not exclude other elements or steps, and the singular does not exclude the plural. A plurality of units or means recited in the system claims may also be implemented by one unit or means in software or hardware. The terms first, second, etc. are used to denote names, but not any particular order.

While exemplary embodiments have been particularly shown and described, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the claims. The protection sought herein is as set forth in the claims below. These and other aspects of the various embodiments are specified in the following numbered clauses:

1. a method in a user equipment for analog CSI feedback, wherein the method comprises:

a, obtaining an analog CSI matrix corresponding to user equipment, wherein the analog CSI matrix meets the following conditions:

X X^H＝D

wherein X represents an analog CSI matrix, H represents a conjugate transpose of the matrix, and D represents a diagonal matrix;

and b, acquiring main element information corresponding to the analog CSI matrix according to preset index information, and sending the main element information to a base station.

2. The method of clause 1, wherein the step b comprises:

b1, extracting the main element information in the analog CSI matrix according to the preset index information, and sending the main element information to a base station.

3. The method of clause 2, wherein the step b1 further comprises:

permuting rows of the analog CSI matrix according to a permutation matrix;

and extracting main element information in the matrix obtained by replacement according to the preset index information, and sending the main element information to a base station.

4. The method of clause 1, wherein the step b comprises:

b2, obtaining a conversion matrix corresponding to the analog CSI matrix according to the preset index information, and converting the analog CSI matrix based on the conversion matrix;

b3 extracting all non-zero elements in the converted matrix, and sending the non-zero elements to a base station as main element information corresponding to the analog CSI matrix.

5. The method of any of clauses 1-4, wherein the analog CSI matrix comprises a first analog matrix and a second analog matrix, the step a comprising:

a1 obtaining a main basis vector of a subspace of channel statistics by decomposing a channel covariance matrix, and determining the first simulation matrix according to the main basis vector;

a2, estimating a linear combination matrix corresponding to the first simulation matrix according to a downlink reference signal from a base station, performing singular value decomposition on the linear combination matrix to obtain corresponding main singular values and main right singular vectors, and obtaining the second simulation matrix according to the main singular values and the main right singular vectors;

wherein the step b comprises:

acquiring main element information corresponding to the first simulation matrix according to the preset index information, and sending the main element information corresponding to the first simulation matrix to a base station in a long-period mode;

and acquiring main element information corresponding to the second simulation matrix according to the preset index information, and sending the main element information corresponding to the second simulation matrix to a base station in a short-period mode.

6. The method of clause 5, wherein the base station employs a cross-polarized antenna array, and the step a1 comprises:

averaging channel covariance matrixes in two polarization directions, decomposing a matrix obtained by performing averaging operation to obtain a main basis vector of a subspace of channel statistics, and determining a first analog matrix corresponding to the user equipment according to the main basis vector;

wherein the step a2 includes:

estimating two linear combination matrixes respectively corresponding to the two polarization directions according to a downlink reference signal from a base station, combining the two linear combination matrixes, performing singular value decomposition on the combined matrixes to obtain corresponding main singular values and main right singular vectors, and obtaining a second simulation matrix corresponding to the user equipment according to the main singular values and the main right singular vectors.

7. The method of any of clauses 1-4, wherein the analog CSI matrix comprises a third analog matrix, the step a comprising:

and performing singular value decomposition on an estimated channel matrix estimated by the user equipment to obtain corresponding main singular values and main right singular vectors, and obtaining the third simulation matrix according to the main singular values and the main right singular vectors.

8. A method in a base station for obtaining an analog CSI matrix corresponding to a user equipment, wherein the method comprises:

a, receiving main element information corresponding to an analog CSI matrix from user equipment;

b, obtaining the analog CSI matrix according to preset index information and the main element information;

wherein the analog CSI matrix satisfies the following conditions:

X X^H＝D

where X represents the analog CSI matrix, H represents the conjugate transpose of the matrix, and D represents the diagonal matrix.

9. The method of clause 8, wherein the principal element information is extracted from the analog CSI matrix, the step B comprising:

and calculating other elements except the main element information in the analog CSI matrix according to preset index information and the main element information to obtain the analog CSI matrix.

10. The method of clause 9, wherein the principal element information includes all non-zero elements in the transformed analog CSI matrix, and step B includes:

determining a matrix obtained after converting the analog CSI according to preset index information and the main element information, wherein other elements except the main element information in the converted matrix are zero;

and performing singular value decomposition on the converted matrix to obtain singular values and right singular vectors corresponding to the converted matrix, and obtaining the simulated CSI matrix according to the singular values and the right singular vectors.

11. The method of any of clauses 8-10, wherein the analog CSI matrix comprises a first analog matrix transmitted to the base station in a long-period mode and a second analog matrix transmitted to the base station in a short-period mode.

12. The method of clause 11, wherein the method further comprises:

and obtaining a third simulation matrix corresponding to the user equipment according to the first simulation matrix and the second simulation matrix.

13. A first apparatus in a user equipment for analog CSI feedback, wherein the first apparatus comprises:

a first obtaining device, configured to obtain an analog CSI matrix corresponding to a user equipment, where the analog CSI matrix satisfies the following condition:

X X^H＝D

wherein X represents an analog CSI matrix, H represents a conjugate transpose of the matrix, and D represents a diagonal matrix;

and the first sending device is used for obtaining the main element information corresponding to the analog CSI matrix according to the preset index information and sending the main element information to the base station.

14. The first apparatus of clause 13, wherein the first transmitting apparatus comprises:

and the first sub-sending device is used for extracting main element information in the analog CSI matrix according to the preset index information and sending the main element information to a base station.

15. The method of clause 14, wherein the first sub-transmitting device further comprises:

a row permutation unit, configured to permute rows of the analog CSI matrix according to a permutation matrix;

and the second sub-sending device is used for extracting the main element information in the matrix obtained by replacement according to the preset index information and sending the main element information to the base station.

16. The first apparatus of clause 13, wherein the first transmitting apparatus comprises:

the conversion device is used for obtaining a conversion matrix corresponding to the analog CSI matrix according to preset index information and converting the analog CSI matrix based on the conversion matrix;

and the third sub-sending device is used for extracting all non-zero elements in the converted matrix and sending the non-zero elements to the base station as main element information corresponding to the analog CSI matrix.

17. The first apparatus of any of clauses 13-16, wherein the analog CSI matrix comprises a first analog matrix and a second analog matrix, the first obtaining means comprising:

first sub obtaining means for obtaining a master basis vector of a subspace of channel statistics by decomposing a channel covariance matrix, and determining the first simulation matrix according to the master basis vector;

second sub-obtaining means for estimating a linear combination matrix corresponding to the first simulation matrix based on a downlink reference signal from a base station, performing singular value decomposition on the linear combination matrix to obtain corresponding main singular values and main right singular vectors, and obtaining the second simulation matrix based on the main singular values and the main right singular vectors;

wherein the first transmitting device comprises:

a fourth sub-transmitting device, configured to obtain, according to the predetermined index information, main element information corresponding to the first analog matrix, and transmit, in a long-cycle mode, the main element information corresponding to the first analog matrix to a base station;

and the fifth sub-sending device is used for obtaining the main element information corresponding to the second simulation matrix according to the preset index information and sending the main element information corresponding to the second simulation matrix to the base station in a short-period mode.

18. The method of clause 17, wherein the base station employs a cross-polarized antenna array, the step first sub-obtaining means comprising:

third sub-obtaining means for averaging the channel covariance matrices in the two polarization directions, obtaining a main basis vector of a subspace of channel statistics by decomposing a matrix obtained by performing an averaging operation, and determining a first analog matrix corresponding to the user equipment according to the main basis vector;

wherein the second sub-obtaining means includes:

a fourth sub-obtaining device, configured to estimate two linear combination matrices respectively corresponding to the two polarization directions according to a downlink reference signal from the base station, combine the two linear combination matrices, perform singular value decomposition on the combined matrices, obtain corresponding main singular values and main right singular vectors, and obtain a second simulation matrix corresponding to the user equipment according to the main singular values and the main right singular vectors.

19. The first apparatus of any of clauses 13-16, wherein the analog CSI matrix comprises a third analog matrix, the first obtaining means comprising:

and a fifth sub-obtaining device, configured to perform singular value decomposition on the estimated channel matrix estimated by the user equipment to obtain corresponding main singular values and main right singular vectors, and obtain the third simulation matrix according to the main singular values and the main right singular vectors.

20. A second apparatus in a base station for obtaining an analog CSI matrix corresponding to a user equipment, wherein the second apparatus comprises:

first receiving means for receiving principal element information corresponding to the analog CSI matrix from the user equipment;

second obtaining means for obtaining the analog CSI matrix according to the main element information and predetermined index information;

wherein the analog CSI matrix satisfies the following conditions:

X X^H＝D

where X represents the analog CSI matrix, H represents the conjugate transpose of the matrix, and D represents the diagonal matrix.

21. The second apparatus of clause 20, wherein the principal element information is extracted from the analog CSI matrix, the second obtaining means comprising:

and calculating other elements except the main element information in the analog CSI matrix according to the preset index information and the main element information to obtain the analog CSI matrix.

22. The second apparatus of clause 20, wherein the principal element information includes all non-zero elements in the converted analog CSI matrix, the second obtaining means comprising:

a determining device, configured to determine, according to the main element information and predetermined index information, a matrix obtained by converting the analog CSI, where other elements except for the main element information in the converted matrix are zero;

and a sixth sub-obtaining device, configured to perform singular value decomposition on the converted matrix, obtain a singular value and a right singular vector corresponding to the converted matrix, and obtain the simulated CSI matrix according to the singular value and the right singular vector.

23. The second apparatus of any of clauses 20-22, wherein the analog CSI matrix comprises a first analog matrix transmitted to the base station in a long periodicity pattern and a second analog matrix transmitted to the base station in a short periodicity pattern.

24. The second apparatus of clause 23, wherein the second apparatus further comprises:

a seventh sub-obtaining device, configured to obtain a third simulation matrix corresponding to the user equipment according to the first simulation matrix and the second simulation matrix.

25. A system for analog CSI feedback, wherein the system comprises a first apparatus as set forth in any of clauses 13-19 and a second apparatus as set forth in any of clauses 20-24.

26. A method in a user equipment for analog CSI feedback, wherein the method comprises:

x, decomposing a channel covariance matrix to obtain a main basis vector of a subspace of channel statistics, and determining a first analog matrix corresponding to the user equipment according to the main basis vector;

y, estimating a linear combination matrix corresponding to the first analog matrix according to a downlink reference signal from a base station;

and z, sending the first simulation matrix to a base station in a long period mode, and sending the associated feedback information corresponding to the linear combination matrix to the base station in a short period mode.

27. The method of clause 26, wherein the step Z comprises:

performing singular value decomposition on the linear combination matrix to obtain corresponding main singular values and main right singular vectors, and obtaining a second simulation matrix corresponding to the linear combination matrix according to the main singular values and the main right singular vectors;

and sending the first simulation matrix to the base station in a long-period mode, and sending the second simulation matrix to the base station in a short-period mode as the associated feedback information.

28. A method in a base station for obtaining CSI feedback information corresponding to a user equipment, wherein the method comprises:

receiving a first analog matrix sent to the base station by user equipment in a long period mode and associated feedback information corresponding to a linear combination matrix sent to the base station in a short period mode;

and obtaining CSI feedback information corresponding to the user equipment according to the first simulation matrix and the associated feedback information.

29. The method of clause 28, wherein the correlated feedback information is a second simulation matrix corresponding to the linear combination matrix.

30. A third apparatus for analog CSI feedback in a user equipment, wherein the third apparatus comprises:

third obtaining means for obtaining a master basis vector of a subspace of channel statistics by decomposing a channel covariance matrix, and determining a first analog matrix corresponding to the user equipment according to the master basis vector;

estimating means for estimating a linear combination matrix corresponding to the first analog matrix according to a downlink reference signal from a base station;

and the second sending device is used for sending the first analog matrix to a base station in a long period mode and sending the associated feedback information corresponding to the linear combination matrix to the base station in a short period mode.

31. The third apparatus of clause 30, wherein the second transmitting apparatus comprises:

a fifth obtaining device, configured to perform singular value decomposition on the linear combination matrix to obtain corresponding main singular values and main right singular vectors, and obtain a second simulation matrix corresponding to the linear combination matrix according to the main singular values and the main right singular vectors;

and a third sending device, configured to send the first analog matrix to the base station in a long-period mode, and send the second analog matrix to the base station in a short-period mode as the associated feedback information.

32. A fourth apparatus in a base station for obtaining CSI feedback information corresponding to a user equipment, wherein the fourth apparatus comprises:

a second receiving device, configured to receive a first analog matrix sent by a user equipment to the base station in a long-period mode, and associated feedback information corresponding to a linear combination matrix sent to the base station in a short-period mode;

and a fourth obtaining device, configured to obtain CSI feedback information corresponding to the ue according to the first analog matrix and the associated feedback information.

33. The fourth apparatus of clause 32, wherein the associative feedback information is a second analog matrix corresponding to the linear combination matrix.

34. A system for analog CSI feedback, comprising a third apparatus as set forth in clause 30 or 31, and a fourth apparatus as set forth in clause 32 or 33.

Claims (10)

1. A method in a user equipment for analog CSI feedback, wherein the method comprises:

a. obtaining an analog CSI matrix corresponding to user equipment, wherein the analog CSI matrix meets the following conditions:

X X^H＝D

wherein X represents an analog CSI matrix, H represents a conjugate transpose of the matrix, and D represents a diagonal matrix;

b. and acquiring main element information corresponding to the analog CSI matrix according to preset index information, and transmitting the main element information to a base station, wherein the preset index information comprises preset index information which can indicate each element which needs or does not need to be transmitted to the base station.

2. The method of claim 1, wherein the step b comprises:

b1. and extracting main element information in the analog CSI matrix according to the preset index information, and sending the main element information to a base station.

3. The method of claim 1, wherein the step b comprises:

b2. obtaining a conversion matrix corresponding to the analog CSI matrix according to the preset index information, and converting the analog CSI matrix based on the conversion matrix;

b3. and extracting all non-zero elements in the converted matrix, and sending the non-zero elements to a base station as main element information corresponding to the analog CSI matrix.

4. The method according to any one of claims 1 to 3, wherein the analog CSI matrix comprises a first analog matrix and a second analog matrix, the step a comprises:

a1. decomposing a channel covariance matrix to obtain a main basis vector of a subspace of channel statistics, and determining the first simulation matrix according to the main basis vector;

a2. estimating a linear combination matrix corresponding to the first simulation matrix according to a downlink reference signal from a base station, performing singular value decomposition on the linear combination matrix to obtain a corresponding main singular value and a main right singular vector, and obtaining the second simulation matrix according to the main singular value and the main right singular vector;

wherein the step b comprises:

acquiring main element information corresponding to the first simulation matrix according to the preset index information, and sending the main element information corresponding to the first simulation matrix to a base station in a long-period mode;

and acquiring main element information corresponding to the second simulation matrix according to the preset index information, and sending the main element information corresponding to the second simulation matrix to a base station in a short-period mode.

5. A method in a base station for obtaining an analog CSI matrix corresponding to a user equipment, wherein the method comprises:

A. receiving main element information corresponding to the analog CSI matrix from user equipment;

B. obtaining the simulation CSI matrix according to preset index information and the main element information;

wherein the analog CSI matrix satisfies the following conditions:

X X^H＝D

wherein X represents an analog CSI matrix, H represents a conjugate transpose of the matrix, and D represents a diagonal matrix;

wherein the predetermined index information includes predetermined index information capable of indicating respective elements that need or need not be transmitted to the base station.

6. The method of claim 5, wherein the principal element information is extracted from the analog CSI matrix, the step B comprising:

and calculating other elements except the main element information in the analog CSI matrix according to preset index information and the main element information to obtain the analog CSI matrix.

7. The method of claim 5, wherein the principal element information includes all non-zero elements in the converted analog CSI matrix, and wherein step B comprises:

determining a matrix obtained after converting the analog CSI according to preset index information and the main element information, wherein other elements except the main element information in the converted matrix are zero;

and performing singular value decomposition on the converted matrix to obtain singular values and right singular vectors corresponding to the converted matrix, and obtaining the simulated CSI matrix according to the singular values and the right singular vectors.

8. A first apparatus in a user equipment for analog CSI feedback, wherein the first apparatus comprises:

a first obtaining device, configured to obtain an analog CSI matrix corresponding to a user equipment, where the analog CSI matrix satisfies the following condition:

X X^H＝D

wherein X represents an analog CSI matrix, H represents a conjugate transpose of the matrix, and D represents a diagonal matrix;

and the first sending device is used for obtaining main element information corresponding to the analog CSI matrix according to preset index information and sending the main element information to the base station, wherein the preset index information comprises preset index information which can indicate each element needing or not needing to be sent to the base station.

9. A second apparatus in a base station for obtaining an analog CSI matrix corresponding to a user equipment, wherein the second apparatus comprises:

first receiving means for receiving principal element information corresponding to the analog CSI matrix from the user equipment;

second obtaining means for obtaining the analog CSI matrix according to predetermined index information and the main element information;

wherein the analog CSI matrix satisfies the following conditions:

X X^H＝D

wherein X represents an analog CSI matrix, H represents a conjugate transpose of the matrix, and D represents a diagonal matrix;

wherein the predetermined index information includes predetermined index information capable of indicating respective elements that need or need not be transmitted to the base station.

10. A system for analog CSI feedback, wherein the system comprises the first apparatus of claim 8, and the second apparatus of claim 9.

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